To transfer real-time data/ notifications you either need to continuously hit the web-server to get the latest notifications or establish a web-socket between server and client.

Hitting web-server is poor in terms of performance especially in PHP, if taken causally. So, the next option is to use Web Sockets.

You mentioned both PHP and Node..

So, if you are using PHP Ratchet is a beautiful library for web-sockets in PHP.

For node express-ws works great as already pointed out by Anuj Sharma

the question is if you want to add the extra language or not you can have similar results by just using zeroMQ or another message queue service if you wanna remain in php.

https://www.youtube.com/watch?v=h8jo3GnKhWM

a talk from the php meetup uk

deepstream.io

Why you are using PHP for sending server side notification ?

Use websocket (express-ws) module of with nodeJS. This is super easy and for debug use this chrome extension "chrome-extension://pfdhoblngboilpfeibdedpjgfnlcodoo/index.html" .

If you need any help ask anytime on Hashnode.